Air distribution unit



W. W. KENNEDY AIR DISTRIBUTION UNIT Aug. 23, 1955 Filed May 3, 1950 Aug. 23, 1955 w. w. KENNEDY 2,715,367

AIR DISTRIBUTION UNIT Filed May a, 1950 :5 Sheets-Sheet 2 IN VEN TOR.

h/a/ er 14 Kennedy a em i w wfw p ATTORNEYS Aug. 23, 1955 w. w. KENNEDY 2,715,867

AIR DISTRIBUTION UNIT Filed May 5, 1950 3 Sheets-Sheet 3 I N V EN TOR. h a/L ex M Kennedy ATTORNEYS United States Patent 0 AIR DISTRIBUTION UNIT Walter W. Kennedy, Rockford, Ill., assi or to Barber- Colman Company, Rockford, 111., a corporation of Illinois Application May 3, 1950, Serial No. 159,795

9 Claims. (Cl. 98-40) This invention relates to air distribution units of the type usually mounted in ceilings and comprising a plurality of deflector members arranged one within the other and cooperating to define one or more axially alined downwardly flaring air passages. The invention has more particular reference to an air distribution unit of the type in which the deflectors are adjustable axially relative to each other by virtue of their mounting on or suspension at spaced points along radially disposed angularly spaced arms or bars fulcrumed at their outer ends to swing about stationary axes disposed adjacent the outer deflector, the inner ends of said rods terminating adjacent each other and the center axis of the distribution unit.

The general object is to provide a unit of the above character in which the deflector members are supported in a novel manner for axial adjustment in unison, which is simple in construction, which does not rely on friction to maintain the deflectors in adjusted positions, which facilitates adjustment of the deflector members from the exterior of the unit, and which operates differentially so as to maintain a predetermined positional relationship between the deflector members in all of their different positions of adjustment.

Another object is to adjust the supporting bars through the medium of a movable actuating element which extends along the center axis of the unit and is readily accessible from the exterior thereof.

A further object is to interconnect the inner ends of the deflector supporting bars and the actuating element to form a frame structure which is suspended from the outer pivots of the bars and is normally rigid but is adapted, in response to movement of the actuating element, to shift axially and vary the inclination of the bars and the axial positions of the deflectors.

A more detailed object is to form the frame structure as a closed linkage which, by movement of the actuating element in opposite directions, is adapted to be expanded and collapsed to shift the frame axially and thereby swing the supporting bars.

Another object is to utilize as the actuating element a rotary shaft disposed on the center of the distribution unit and itself constituting part of the closed linkage.

The invention also resides in the novel construction and manner of collapsing the closed linkage and in the mouting of the supporting bars and the floating linkage to permit ready removal of the unitary assembly formed by the linkage and the inner and intermediate deflectors.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which:

Figure l is a fragmentary diametrical cross-sectional view of an air distribution unit embodying the novel features of the present invention.

2,715,867 Patented Aug. 23, 1955 Fig. 2 is a fragmentary plan sectional view taken along the line 22 of Fig. 1.

Fig. 3 is a fragmentary sectional View taken along the line 33 of Fig. 2.

Figs. 4, 5, and 6 are schematic views of the improved distribution unit showing different positions of adjustment of the deflector members.

Fig. 7 is a fragmentary sectional view similar to Fig. 1 showing a modification.

While the invention is susceptible of various modifications and alternative constructions, I have shown in the drawings and will herein describe in detail the preferred embodiment. It is to be understood, however, that I do not intend to limit the invention by such disclosure, but aim to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

In the form illustrated in the drawings, the improved distribution unit is intended to be set into a ceiling 9 or other wall of a room into which air supplied from a duct 10 is delivered through a plurality of axially alined passages 11 and 12 of different sizes and discharged into the room in the form of streams 13 and 14. Instead of forcing air through all of the passages, one of the latter, preferably the inner one, may be used to convey return air out of the room.

Each of the air passages 11 and 12 is defined by a pair of deflector members one arranged within the other and spaced along a common axis. Where, as in the present instance, there are two air passages through the unit, three deflector members 16, 17, and 18 are employed, the passage 11 being defined by the outer and intermediate members 16 and 17 While the passage 12 is formed by the intermediate member coacting with the inner or central member 18. The number of air passages may, of course, be increased by employing additional intermediate deflector members, the crosssectional shape of which corresponds to the desired cross section of the air passages. In the present instance, the deflector members and, therefore, the passage are annular but, of course, may be of square, rectangular, or other preferred cross section while remaining in a gen erally concentric relation.

Herein, the outer deflector member 16 comprises a generally frusto conical shell having a cylindrical neck or inlet end 19 telescoping with and suitably secured to a flange 20 which constitutes a branch of a supply duct 10. Immediately below the larger end of the cone, the shell is made generally cylindrical as indicated at 21 and then is bent outwardly substantially at right angles to form a peripheral decorative flange 22 gradually sloping backwardly and terminating in a bead 23 which abuts against the ceiling surface in the final installation.

The intermediate deflector 17 is similarly shaped but is a smaller and somewhat steeper hollow truncated cone also composed of sheet metal and having at its inner end a short cylindrical neck 24 concentric with the outer neck 19 but spaced axially and inwardly from the latter. The larger or outer edge portion of the cone 17 is bent to form a generally cylindrical portion 21 and a substantially right angular slightly sloping flange 26 of the same general contour as the flange 22 but slightly narrower in width than the latter. The flange 26 is somewhat smaller in diameter than the flange 22 but larger than the neck 19 so as to project outwardly partially across the conical portion of the shell 16.

Disposed substantially perpendicular to the axis of the unit is the inner deflector member 18 which herein comprises an imperforate disk having an outer peripheral flange 27 of the same general contour as the flanges 22 and 26 and somewhat larger in diameter than the neck 24 so that the cross-sectional area of the annular passage 18 are supported from the outer shell 16 for axial adjust- 3 ment in unison but differentially through proportionately greater distances to enable the direction of discharge of the air streams 13 and 14 to be varied while maintaining the ratio of the cross-sectional areas of the passages 11 and 12 substantially constant, and this, without detracting from the artistic external appearance of the unit. Thus, the members 17 and 18 may be positioned with their flanges 26 and 27 substantially flush with the flange 22 (Fig. 4), or spaced inwardly diflerent distances from the flange 22 as shown in Fig. 5, or spaced outwardly as shown in Fig. 6.

The mounting for effecting the differential adjustment of the movable members comprises a plurality of lever arms 30 disposed within the neck portion of the shell 16 and radiating outwardly from the axis thereof with each P arm pivotally connected at its outer and inner ends to the shell 16 and the inner deflector 18 and intermediate its'ends to the intermediate deflector 17. Herein, the three arms are angularly spaced equal distances apart around the axis of the unit, and each comprises a substantially straight rigid bar disposed edgewise relative to the direction of air flow through the unit with the outer end of the bar loosely received between two brackets 31 projecting inwardly from and welded to the inner side of the neck 19. A tangentially disposed cross pin 32 rigid with and spanning the brackets extends through a longitudinally elongated slot 33 in the bar end. On its lower edge, the outer end of the slot is opened as indicated at 34 to permit the bar 30 to be lifted off and unhooked from the .pins 32 and the entire inner assembly including the intermediate and inner members 17 and 18 to be removed from the outer shell. Convenient access to the interior of the unit or to the duct is thus afforded.

Intermediate their ends but at points spaced a short distance outwardly from their centers, the bars are longitudinally slotted as indicated at 35 to receive pins 36 which parallel the respective pins 32 and span radially spaced bracket plates 37 welded or otherwise secured to the neck 24 on the interior of the latter. In the form shown, the bars project across the inner ends of the neck 24, but where the intermediate member 17 is utilized as the outer wall of a return air passage'through the unit, the bars are extended through slots in the extended neck 24.

The intermediate deflector 17 is thus suspended from the bars 30 and is adjusted axially as an incident to changing the horizontal inclination of the bars by swinging the latter about the fulcrums 32, the amount of such adjustment for a given change in the bar inclination corresponding to the spacing of the pivots 32 and 36. Sinai lar proportionate adjustment of the inner de ester 18 is achieved by suspending the latter in a manner to be described presently from the inner end portion of the bars 30. In accordance with one aspect of the present invention, the inclination of the deflector supporting bars 30 is varied by movement of an actuating element which extends along the center axis of the distribution unit and preferably takes the form of a rotary shaft 45. In another aspect of the invention, the shaft cooperates with the inner end portion of at least one of the bars 36 and with one or more links 41 to form a framework or closed linkage A which is normally rigid so as to hold the bars 30 at a fixed inclination but which is changeable in shape in response to movement of the actuating element to correspondingly vary the inclination of the bars and therefore the axial positions of the deflectors 17 and 18 suspended therefrom.

Considering now the details of the exemplary linkage herein shown, the bars 30 at points disposed near but spaced outwardly from their inner ends, are fulcrumed on pivot pins 38 which are fixed relative to the bars and supported on the disk 18 but spaced inwardly from the plane thereof. To this end, bracket arms 39 welded to the top of the disk'lS at angularly spaced points converge upwardly and inwardly and are secured at their inner'ends to a plate 46 which is spaced axially from the disk a distance approximately equal to the axial height of the intermediate deflector member 17. Radially disposed cars 41 are struck out of peripheral portions of the plate 40 and are riveted to the pivot pins 38 which extend parallel to the pins 36.

To form the closed linkage above referred to, each bar 30 is pivotally and slidably connected at a fourth point to the one of the deflector members having the fixed pivotal connection, that is, the inner member 18 in this instance. This connection includes a longitudinal slot 42 (Fig. 3) formed at the extreme inner end of each bar 30 and receiving a cross pin 43 paralleling the pins 32, 36, and 38, and spanning an outwardly opening slot formed at a disk 44 and straddling the end of the bar. The pins 43 are supported in angularly spaced tangentially disposed relation on the disk which is spaced above the plate 40 and supported by the latter.

With the pivots 38 and 43 carried by the same one of the deflector members and connected to the bars 30 at spaced points along the latter, the bars are held against swinging relative to this member so that the ars and the intermediate and inner deflector members 17 and 18 constitute a relatively rigid assembly which may be suspended within the outer shell 16 by hooking the outer ends of the bars over the pivot pins 32.

By virtue of this same spaced pivotal connection between the member 18 and the bars 30, the latter may be rocked up or down relative to the member 18 and about the fixed fulcrum 38 simply by shifting the pins 43 downwardly or upwardly along the axis of the unit thereby varying the axial positions of the intermediate and inner members in proportion to the spacing of their supporting pivots 36 and 38 inwardly from the supporting pivots 32 on'the outer shell. While such adjustment of the pivot pins 43 may be effected in various ways, it is produced in the present instance by turning in one direction or the other the actuating element or shaft 45 which as described above extends along the axis of the distributing unit with one end accessible from an external point such as the bottom of the inner deflector member 18 wherein the shaft end projects through a hole in the disk center 28 and is suitably formed as indicated at 46 to receive a tool by which the shaft may be turned. Near its upper end, the shaft is journaled in the plate 40 and is supported on the latter against movement in either direction by a collar 40 and a pin 4W fixed to the shaft on opposite sides of the plate. The rotary motion of the shaft is converted into axial movement of the pins 43 by a screw mechanism comprising a thread 49 formed on the upper end of the shaft and mating with an internal thread in a hole in the disk 44 on which the pins 43 are sup ported. By turning the shaft, the disk or nut 44 will be advanced up or down relative to the plate itl'thus correspondingly rocking the bars 30 about the fulcrum pins 38. Such rocking is accompanied by raising or lowering of the inner and intermediate members 18 and 17 inasmuch as the pins 32 are fixed in the final installation. Owing to the close spacing of the pins 38 and as compared to the length of the levers, the axial adjustment of the inner member will be several times the distance that the nut 44 is advanced relative to the plate 40.

It will be observed that rocking of the bars 30 between the extreme positions shown in dotted and phantom outline in Fig. 1 is accompanied by corresponding changes in the effective length'of the bars since the radial spacing of the pins 32 and 38 remains fixed. Such elongation is made possible by virtue of the slots 33 and 42. Thus, in the extreme positions of the bars, the pins 32 and 43 will be disposed in the outer ends of these slots, while in the intermediate position shown in full in Fig. l in which the bars are disposed substantially perpendicular to the axis of the distribution unit, the bars will be of shortest effective length and the pins will be disposed near the inner ends of the slots 33 and 42. The amount of permissible axial adjustment of the inner unit 18 will, it will be seen, be determined by the lengths of the slots 33 and 42.

From the foregoing, it will be seen that the inner end portion of the bar 30 between the pivots 38 and 43, the part of the actuating shaft between the nut and the collar 40*, and the rigid link 41 form a closed triangle which is normally rigid but which may be expanded or collapsed by turning the shaft opposite directions, such expansion or collapse being accompanied by a corresponding change in the inclination of that part of the linkage formed by the bars 30. The part of the linkage formed by the ears 41 and the plate 40 constitutes a rigid link extending outwardly from the rotary connection 40, 40 with the shaft 45 and then along the shaft to the point 38 of pivotal connection of the other end of the link with the bar 30. The third part of the linkage is formed by the nut 44 and that length of the shaft between the nut and the abutments 40 40*, this link normally being of fixed length by virtue of the threaded connection at one end and the abutments 40 and 40 at the other end. Since the shaft is journaled in the axially spaced members 40 and 44 at opposite ends of this link and since one of the connections is a cam or thread, the length of the link and therefore the shape of the triangular linkage may be changed by turning the shaft in opposite directions, the inclination of the bars 30 being varied correspondingly.

Some of the different positions to which the deflectors may be shifted in response to changes in the shape of the linkage A so as to discharge the air in diiferent patterns are illustrated in Figs. 1, 4, 5, and 6. As shown in full in Fig. 1 and in Fig. 4, the flanges 22, 26, and 27 of the three members lie in a common plane. This flush relationship is achieved by forming the three members with their flanges spaced axially equal distances from the pivot pins 32, 36, and 38. With the deflectors thus positioned, the cylindrical lower end portions 21 and 21' of the outer and intermediate members 16 and 17 will not produce a substantial downward bending of the air streams 13 and 14. As a result, the streams will flare outwardly at a relatively small angle as illustrated in Fig. 4, the combined depth of the two streams outwardly beyond the unit and below the ceiling being relatively shallow.

If it is desired to produce a thicker combined air stream flowing outwardly at a still smaller angle relative to the ailing, the inner and intermediate members 17 and 18 are adjusted outwardly as shown in Fig. 6. This is accomplished by turning the shaft 45 in a direction to lower the nut 44 relative to the plate 40 thus tipping the outer ends of the levers 30 upwardly from the plane of the plate as shown in dotted outline in Fig. 1. This is accompanied by an elongation of the levers as permitted by sliding of the pins 32 and 43 outwardly along the slots 33 and 42, the pins 36 of the intermediate member 17 automatically finding new positions along the slots 35.

From a comparison of Figs. 4, 5, and 6, it will be apparent that although the intermediate and inner deflector members are moved differentially in response to turning of the adjusting shaft, the ratio of the two movements remains fixed as determined by the spacing of the pivot pins 32, 36, and 38. As a result, corresponding points on the flanges 22, 26, and 27 are always alined, that is to say, the flanges lie in a single plane in the flush position (Fig. 4), on the exterior of a downwardly converging cone (Fig. 6), or on the interior of an upwardly 6 converging cone (Fig. 5). The result of this is to maintain an artistic appearance on the face of the unit and to maintain substantially constant the ratio of the crosssectional areas of the air passages 11 and 12.

The unit may be adjusted as shown in Fig. 5 to direct the air streams 11 and 12 downwardly nearly vertically. To this end, the shaft 45 is turned in a direction to raise the nut 44 relative to the supporting plate 40 thus inclining the bars 30 downwardly to the positions shown in dot-dash outline in Fig. 1. This results in raising the inner ends of the bars about the supporting pivots 32 and is accompanied by a corresponding upward adjustment of the intermediate and inner members 17 and 18 to position the latter above the plane of the flange 22. In this relation of the adjustable members, the cylindrical walls 21 and 21 of the members 16 and 17 are more effective in deflecting the air streams 11 and 12 which are thus bent downwardly farther toward the vertical as shown in Fig. 5. The downward throw of the combined air stream is thus increased.

In the case of distribution units of relatively large diameter, it is sometimes desirable to provide additional lateral support for the lower end of the inner member 18. This may be accomplished without interfering with the adjustment of the members as above described by employing braces 51 arranged as shown in Fig. 7. The braces comprise three rigid rods angularly spaced around the axis of the unit with their outer ends disposed between the lower portions of the bracket plates 37 and pivotally connected to the latter by pins 52. These rods converge downwardly between the adjacent bracket arms 39 and at their inner ends are pivotally connected to a ring 53 encircling the shaft 45 and slidable along the latter. The connection includes pivot pins 54 spanning outwardly opening notches spaced around the outer edge of the ring. Since the ring is free to slide on the shaft, the brace rods will, during vertical adjustment of the members 17 and 18 in the manner described above, move up and down as a unit along with the intermediate unit 17.

It will be apparent from the foregoing that the different adjusted positions of the intermediate and inner deflectors 17 and 18 are maintained by virtue of the rigid character of the closed linkage above described. The holding action is achieved positively without telescoping of the deflectors or the use of sliding friction fits therebetween. As a result, the distributor unit may be installed with its axis disposed vertically as in the ceiling of a room. At the same time, the deflectors may be adjusted accurately and conveniently simply by turning the shaft 45 which is readily accessible.

I claim as my invention:

1. An air distribution unit having, in combination, a rotary shaft having a thread thereon, a nut on said shaft mating with said thread to move axially there along during turning of the shaft, a bar radiating outwardly from said shaft, means providing a connection between the inner end of said bar and said nut to permit the bar to swing about a pivot spaced outwardly from said shaft and extending generally tangentially of said nut, inner and outer annular air deflectors both centered on the axis of said shaft and radially spaced apart so as to coact with each other in defining a generally annular passage for the flow of air longitudinally of said shaft axis, means connecting said outer deflector and said bar for relative swinging about a pivot paralleling said first pivot and spaced along the bar outwardly from the latter pivot, means providing a connection including a third pivot on said bar paralleling said first and second pivots and disposed between the latter, a rigid member supported at one end by said third pivot and extending longitudinally of said shaft and inwardly to a point adjacent the shaft, and means providing a connection between the inner end of said member and said inner deflector shiftable axially relative to said nut upon turning of said shaft, one of said connections having parts shiftable relative to each other to permit said axial shifting of said nut and inner member.

.2. An air distribution unit having, in combination, outer and inner wall members having a common axis and spaced apart radially to define an annular air passage between them, an adjusting element mounted on said inner member for adjustment along said axis, a rigid bar extending radially outwardly from said axis, means pivotally connecting said bar to said outer member at a point radially spaced outwardly from said axis for swinging of the bar about an axis extending transversely of the bar, two connections, one between said bar and said adjusting element and the other between the bar and said inner member, each connection including a pivot disposed adjacent the inner end of said bar and having an axis extending transversely of the bar, said pivots being spaced apart along said bar and parts of one of said connections being relatively shiftable to permit said adjusting element to be moved along the axis of the unit, and mating threaded parts respectively connected to said element and said inner member and rotatable relative to each other to effect relative axial movement between said element and said inner member and thereby adjust the angular position of said bar.

3. An air distribution unit having, in combination, means defining two downwardly flaring generally annu lar air passages including an outer deflector part and successively smaller intermediate and inner deflector parts, angularly spaced radially disposed bars having inner ends terminating adjacent each other and the center axis of the unit and outer ends each fulcrumed to swing about a stationary axis disposed adjacent said outer deflector part and extending generally tangentially thereof, a member pivotally connected to said inner bar ends and movable axially of said unit by swinging of the bars about said stationary axes, a second member axially spaced from said first member, a rigid link joined at one end to said second member and pivotally joined at the opposite end to one of said bars at a point spaced outwardly from the inner pivot thereof, a rotary shaft extending axially through said members and rotatable relative thereto, means connecting said shaft and the respective members to unite the shaft, said link and the inner end portion of said one bar into a closed linkage,

said connections normally holding said members against relative axial movement but operating during turning of said shaft in opposite directions to respectively lengthen and shorten the shaft element of said linkage and thereby change the inclination of said bars relative to said shaft, and means spaced along said bars and suspending said intermediate and inner deflector parts therefrom for proportionate axial adjustment during turning of said shaft.

4. An air distribution unit having, in combination,

a means defining at least two downwardly flaring annular air passages including an outer deflector and successively smaller intermediate and inner deflectors, angularly spaced radially disposed bars each fulcrumed at its outer end to swing about a stationary axis extending generally tangentially of said outer deflector, a rotary shaft extending along the center axis of said deflectors, a link extending along said shaft, means pivotally joining said link, said shaft, and the inner end portion of one of said bars to form a closed linkage, means operable upon turning of said shaft in opposite directions to respectively expand and collapse said linkage and thereby vary the inclination of said bars relative to said center axis, and means spaced along said bars and suspending said intermediate and inner deflectors for proportionate axial adjustment during turning of said shaft and the resulting tilting of said bars.

5. An air distribution unit having, in combination, means defining at least two downwardly flaring annular air passages including an outer deflector and successively smaller intermediate and inner deflectors, angularly spaced radially disposed bars each having an inner end disposed adjacent the center axis of the unit and an outer end fulcrumed adjacent said outer deflector to swing aboutan axis extending generally tangentially of such deflector, a rotary screw shaft extending along said first axis, a nut threaded onto said shaft and supporting said inner ends of said bars for swinging about pivots parallel to said fulcrum axes, a link joined at opposite ends to said shaft and to one of said bars at points respectively spaced radially and axially from said pivots whereby to form a closed linkage which is expanded and collapsed upon turning of said shaft in opposite directions to thereby vary the inclination of said bars relative to said first center, and means spaced along said bars and suspending said intermediate and inner deflectors for proportionate axial adjustment during turning of said shaft.

6. An air distribution unit having, in combination, means defining at least two downwardly flaring annular air passages including an outer deflector and successively smaller intermediate and inner deflectors, angularly spaced radially disposed bars each fulcrumed at its outer end to swing about an axis extending generally tangentially of said outer deflector, an element extending along the center axis of said deflectors, a link connected at one end to said element, means connecting said bar to said element and to the other end of said link at points radially spaced along the bar to form a normally rigid closed linkage supported solely by the fulcrurns of said bars for bodily movement along said center axis, said connecting means including pivots to permit flexing of the linkage and said element having means operable from a point exteriorly of said unit for elongating or shortening the effective length of said element to flex and change the shape of said linkage and thereby vary the inclination of said bars, and means spaced along said bars and suspending said intermediate and inner deflectors for proportionate axial adjustment during such change in inclination of said bars.

7. An air distribution unit having, in combination, means defining at least two downwardly flaring annular air passages including a stationary outer deflector and successively smaller intermediate and inner deflectors, angularly spaced radially disposed bars having outer and inner ends respectively terminating adjacent said outer deflector and the center axis thereof, means spaced along said bars and pivotally suspending said intermediate and inner deflectors therefrom, an elongated element extending along the central axis of said unit, means constituting a triangular closed linkage having one leg formed by the inner end of one of said bars and another leg formed by said element, means detachably joining the outer ends of said bars to said outer deflector to support said unit solely from the outer deflector while permitting ready separation of the unit therefrom, said last mentioned means having pivots fulcruming said bars for swinging about axes fixed relative to said outer deflector and extending transversely of the bars, and means selectively operable to change effective length of said element and thereby vary the shape of said linkage and the inclination of said bars relative to said axis.

8. An air distribution unit having, in combination, means defining at least two downwardly flaring annular air passages including a stationary outer deflector part and successively smaller intermediate and inner deflector parts, angularly'spaced radially disposed bars having outer and inner ends respectively terminating adjacent said outer deflector part and the center axis thereof, means spaced along said bars and pivotally suspending said intermediate and inner deflector parts therefrom, an elongated element extending along the central axis of said unit, means constituting a triangular closed linkage having one leg formed by one of said bars and another leg formed by said element, means joining the outer ends of said bars to said outer deflector part and including pivots fulcruming said bars to swing about axes fixed relative to said outer deflector part and'extending transversely of thebars, and

selectively operable means for lengthening or shortening the effective length of said element and thereby vary the shape of said linkage and the inclination of said bars relative to said axis.

9. An air distribution unit having, in combination, angularly spaced bars generally radiating from the center of the unit, means defining a plurality of downwardly flaring generally concentric air passages and including an outer deflector part and successively smaller intermediate and inner deflector parts pivotally suspended from said bars at points radially spaced along the latter, the outer ends of said bars being fulcrumed to swing about stationary axes disposed adjacent said outer deflector part and extending normal to the corresponding bars, a rotary shaft extending along the center axis of said unit, a first member journaled on said shaft, means holding said member against axial movement relative to said shaft and joining the member to said inner deflector part, a second member axially spaced along said shaft from said first member and threaded on the shaft to move toward and away from the first member as the shaft is turned back an iorth, means pivotally connecting the inner ends of said bars to one of said members, a link, means connecting said linl; at one end to one of said bars at a point spaced outwardly from the central axis of said unit and at the other end to the other of said members to form a closed linkage with said one bar and said shaft whereby turning of said shaft in opposite directions causes said linkage to expand and collapse thereby to vary the inclination of said bars relative to said center axis and effect proportionate axial adjustment of said intermediate and inner deflector parts.

References Cited in the file of this patent UNITED STATES PATENTS 2,125,454 Marshall Aug. 2, 1938 2,355,294 Herbster Aug. 8, 1944 2,365 "67 Dauphinee Dec. 26, 1944 2,627,799 Kurth et al Feb, 10, 1953 FOREIGN PATENTS 365,048 Great Britain Jan. 11, 1932 

